Postoperative epidural hematoma covering the galeal flap in pediatric patients with moyamoya disease: clinical manifestation, risk factors, and outcomes

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Postoperative epidural hematoma (EDH), a blood collection between the inserted galeal flap and the overlying skull flap (epigaleal flap hematoma), is a frustrating complication of the surgical treatment of moyamoya disease (MMD) in pediatric patients. The symptoms of postoperative EDH are often similar to those of postoperative cerebral ischemia, and may cause confusion during clinical decision making. The authors designed this study to evaluate the incidence, clinical presentation, risk factors, and treatment outcomes of postoperative EDH in pediatric patients with MMD. A retrospective review of 148 pediatric patients with 250 craniotomies who underwent indirect bypass revascularization surgery between January 2002 and December 2006 was performed. This group consisted of 60 male and 88 female patients, and the mean age at surgery was 7.5 years (range 1-18 years). Of the 250 craniotomies, postoperative EDH was detected in 32 cases. In 12 cases of EDH, surgical treatment was necessary (4.8% of 250 craniotomies). During the same period, 743 non-MMD craniotomy operations were performed. In 6 of these 743 operations, patients developed postoperative EDH that required surgical treatment, significantly less than the percentage of EDH requiring postoperative treatment in patients with MMD (0.8%, p < 0.001). The average interval between craniotomy surgery and the detection of EDH was 1.8 days (range 0-5 days) in patients with MMD and 0.5 days (range 0-2 days; p = 0.018) in the non-MMD craniotomy group. Postoperative EDH was observed in significantly fewer cases (17 of 191) when a subcutaneous drain (SCD) was inserted over the bone flap than in cases in which an SCD was not inserted (14 of 55; p = 0.001). The mean international normalized ratio of prothrombin time in the immediate postoperative blood test was 1.27 ± 0.17 in the EDH group and 1.20 ± 0.11 in the non-EDH group (values are expressed as the mean ± SD; p = 0.008). Central galeal flap tenting suture and immediate postoperative platelet count were not related to the incidence of postoperative EDH following pediatric MMD surgery. Postoperative EDH is more likely to be found following craniotomy in patients with MMD than in those without MMD, and may occur in a delayed fashion. Insertion of an SCD and immediate correction of an abnormal value for international normalized ratio of prothrombin time can decrease the incidence of postoperative EDH following surgery for pediatric MMD.